A line snaked around Sullivan Gym at the University of Southern Maine as hundreds of people waited Sunday for the doors to open at the Great Portland Bike Swap.

When they did, it was a mad scramble for the hundreds of used bicycles on sale at the annual event sponsored by the Bicycle Coalition of Maine, a statewide group that promotes bicycling. A portion of each sale raised money for the coalition’s programming and education efforts.

Allison Vogt, executive director of the coalition, said about 1,500 people showed up at the swap to sell, buy and browse. Dozens of volunteers were on hand to help.

Hilary Frenkel of Portland snagged a $250 hybrid that she plans to use to commute to work. She was one of the first in line to pay for her new wheels. It helped that Frenkel was manning a booth at the sale.

“So I missed the madhouse,” she said.